what is it telling us? >> this study focused on women with the brc mutation, a human gene when it's abnormal or mutated it has been linked to about 10% of hereditary breast cancer and 9% of ovarian cancer. this study was ground-breaking because it was the first one that showed it saved lives. it looked at 2500 women over four countries, followed them for an average of four years. and found that those with the brca mutation who had this risk-reducing surgery decreased their risk of dying of cancer by 70% to 80%. >> those numbers are amazing. anyone who's been touched by cancer is immediately going to sit up and look at that. but this is, as you mentioned, a high-risk surgery. talk to us, what are we talking about specifically when it comes to the surgery? >> right. when you talk about preventive surgery or risk-reducing surgery, you have to take into account not just the risks of the procedure but the age of the patient, have they had children? do they want future children? and also what are the consequences